package com.paas.util;

import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.extern.slf4j.Slf4j;

import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.security.MessageDigest;
import java.util.Random;
import java.util.UUID;

/**
 * @author pangjs
 * @version 0.1
 * @date 2021/6/19 1:35 下午
 * @description
 */
@Slf4j
public class CommonUtil {


    public static String MD5(String data)  {
        try {
            java.security.MessageDigest md = MessageDigest.getInstance("MD5");
            byte[] array = md.digest(data.getBytes("UTF-8"));
            StringBuilder sb = new StringBuilder();
            for (byte item : array) {
                sb.append(Integer.toHexString((item & 0xFF) | 0x100).substring(1, 3));
            }
            return sb.toString().toUpperCase();
        } catch (Exception exception) {
        }
        return null;

    }

    /**
     * 获取随机数
     * @param length
     * @return
     */
    public static String getRandomCode(int length){
         String sources = "0123456789";
         Random random = new Random();
         StringBuilder sb = new StringBuilder();
         for(int j=0;j<length;j++){
             sb.append(sources.charAt(random.nextInt(9)));
         }
         return sb.toString();
    }

    /**
     * 获取当前时间戳
     */
    public static long getCurrentTimestamp(){
        return System.currentTimeMillis();
    }

    /**
     * 生成uuid
     * @return
     */
    public static String generateUUID() {
        return UUID.randomUUID().toString().replaceAll("-","").substring(0,32);
    }

    /**
     * 获取随机长度的串
     * @param length
     * @return
     */
    private static final String ALL_CHAR_NUM = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
    public static String getStringNumRandom(int length) {
        //生成随机数字和字母,
        Random random = new Random();
        StringBuilder saltString = new StringBuilder(length);
        for (int i = 1; i <= length; ++i) {
            saltString.append(ALL_CHAR_NUM.charAt(random.nextInt(ALL_CHAR_NUM.length())));
        }
        return saltString.toString();
    }

    /**
     * 响应json数据给前端
     *
     * @param response
     * @param obj
     */
    public static void sendJsonMessage(HttpServletResponse response, Object obj) {

        ObjectMapper objectMapper = new ObjectMapper();
        response.setContentType("application/json; charset=utf-8");

        try (PrintWriter writer = response.getWriter()) {
            writer.print(objectMapper.writeValueAsString(obj));

            response.flushBuffer();

        } catch (IOException e) {
            log.warn("响应json数据给前端异常:{}",e);
        }


    }
}
